Cogged v-belt and belt transmission mechanism

Abstract

The present invention relates to a cogged V-belt having, at least on the inner peripheral side, a cog section in which cog peaks and cog valleys are aligned in an alternating manner in the belt longitudinal direction. The cog section is provided with at least a compressed rubber layer, and the compressed rubber layer includes a first rubber layer on the belt inner peripheral side and a second rubber layer further to the belt outer peripheral side than the first rubber layer. The first rubber layer is formed using a first crosslinked rubber composition containing a first rubber component and first short fibers. The second rubber layer is formed using a second crosslinked rubber composition containing a second rubber component and second short fibers. The first rubber layer and the second rubber layer are exposed to form a friction transmission surface, and the elastic modulus of the first rubber layer is lower than the elastic modulus of the second rubber layer.

Description

Cog-equipped V-belt and belt drive mechanism

[0001] The present invention relates to a V-belt with cogs and a belt transmission mechanism for use in a belt-type continuously variable transmission.

[0002] Power transmission belts used in power transmission mechanisms of machinery and other equipment are broadly classified into friction belts and meshing belts based on the method of power transmission. Examples of friction belts include V-belts, V-ribbed belts, and flat belts, while toothed belts are a well-known example of meshing belts.

[0003] V-belts come in two main types: raw-edge V-belts, where the friction transmission surface (V-shaped side) is an exposed rubber layer, and wrapped V-belts, where the friction transmission surface is covered with a cover cloth. The type of belt used depends on the surface properties of the friction transmission surface (the coefficient of friction between the rubber layer and the cover cloth). Raw-edge V-belts include not only raw-edge V-belts without cogs, but also raw-edge cogged V-belts, which have cogs only on the inner circumference to improve flexibility, and raw-edge double cogged V-belts, which have cogs on both the inner and outer circumferences to improve flexibility.

[0004] One application of these cogged V-belts is a belt-type continuously variable transmission (CVT). As shown in Figure 1, the belt-type CVT 30 is a device that continuously changes the gear ratio by winding a V-belt 31 around a drive pulley 32 and a driven pulley 33. Each pulley 32, 33 consists of fixed sheaves 32a, 33a whose axial movement is restricted or fixed, and movable sheaves 32b, 33b that can move in the axial direction, and has a structure that allows the width of the V-groove of the pulleys 32, 33 formed by these fixed sheaves 32a, 33a and movable sheaves 32b, 33b to be continuously changed. The V-belt 31 has tapered surfaces at both ends in the width direction that match the inclination of the opposing surfaces of the V-grooves of each pulley 32, 33, and fits into any position in the pulley radial direction according to the adjusted width of the V-groove. For example, by narrowing the width of the V-groove on the drive pulley 32 and widening the width of the V-groove on the driven pulley 33, the state shown in Figure 1(a) is changed to the state shown in Figure 1(b). This causes the V-belt 31 to move towards the outer circumference in the radial direction of the pulley on the drive pulley 32 side and towards the inner circumference in the radial direction of the pulley on the driven pulley 33 side. As a result, the winding radius around each pulley 32 and 33 changes continuously, allowing for stepless adjustment of the gear ratio. A V-belt used in such a CVT is called a gear shift belt (CVT belt).

[0005] For V-belts, increasing the overall thickness of the belt (i.e., increasing the surface area of ​​the friction transmission surface) is required to improve lateral pressure resistance and transmission capacity. On the other hand, from the perspective of improving bending fatigue resistance and transmission efficiency, it is required to maintain good flexibility by reducing the overall thickness of the belt. The cogs of a cog-type V-belt are designed to meet these conflicting requirements. In other words, in a cog-type V-belt, the cog peaks ensure a large surface area for friction transmission, improving lateral pressure resistance and transmission capacity, while the cog valleys are designed to maintain good flexibility.

[0006] In a cog-type V-belt, a series of bending and unbending movements (bending deformation) of the belt before and after it wraps around the pulley are continuously repeated. Specifically, when the belt is wrapped around the pulley, it bends around the core wire, so bending stress occurs on the outer circumference side of the core wire due to bending deformation, and compressive stress occurs on the inner circumference side of the core wire due to compressive deformation, causing the belt to deform. Then, as the belt moves away from the pulley, this deformation is released. In other words, in a cog-type V-belt, this deformed state (curved shape) and unbending state (planar shape) are repeated during belt movement, but in this series of movements (bending deformation), the bending of the cog valleys is greater than the bending of the cog peaks. As a result, the fatigue of the compression rubber layer that is repeatedly bent in the cog valleys is greater, and cracks are more likely to occur in the compression rubber layer of the cog valleys compared to the cog peaks. In particular, stress due to bending deformation tends to concentrate at the bottom of the cog valleys (including the deepest part of the cog valleys), and various methods have been proposed to alleviate the stress at the bottom of the cog valleys and suppress cracks in the cog valleys.

[0007] For example, Japanese Patent Publication No. 7048824 (Patent Document 1) discloses a cog-covered V-belt in which the cross-sectional shape of the cog valley in the longitudinal direction of the belt comprises a bottom made up of a plurality of continuous arcs and side walls of the cog valley that are inclined with respect to the belt thickness direction, and the plurality of arcs constituting the bottom have a specific shape in which the radius of curvature decreases as they move away from the deepest part of the cog valley. Furthermore, this document states that this cog-covered V-belt can ensure high resistance to lateral pressure and transmission force, and can also alleviate and disperse stress at the bottom of the cog valley where stress tends to concentrate due to bending deformation, thereby suppressing the occurrence of cracks in the cog valley.

[0008] On the other hand, from the viewpoint of improving lateral pressure resistance, it is also required to increase the rigidity (high modulus of elasticity) of the rubber layer, and conventionally, short fibers have been blended into the rubber composition to increase the rigidity of the rubber layer. Furthermore, the short fibers blended into the rubber composition are also oriented in the direction of the belt width. By blending short fibers in this way, the lateral pressure resistance of the cog V-belt is improved, and the wear resistance of the friction transmission surface can also be improved because the short fibers protrude from the friction transmission surface.

[0009] For example, Japanese Patent Publication No. 2024-7332 (Patent Document 2) discloses a rubber composition for use in the compression rubber layer of a power transmission belt, comprising 15 to 38 parts by mass of short fibers, 5 to 28 parts by mass of aramid short fibers, 0.1 to 3.2 parts by mass of an adhesion improver, and 30 to 70 parts by mass of carbon black, per 100 parts by mass of chloroprene rubber. This document states that using the above rubber composition can simultaneously improve the wear resistance, fuel efficiency, and crack resistance of a power transmission belt.

[0010] Japanese Patent No. 7048824 Japanese Patent Publication No. 2024-7332

[0011] However, as shown in Patent Document 2, increasing the rigidity of the compression rubber layer improves lateral pressure resistance but reduces flexibility. On the other hand, even if the method for relieving stress at the bottom of the cog valleys disclosed in Patent Document 1 is adopted, when the belt is bent, stress concentration at the bottom of the cog valleys becomes significant, and the occurrence of cracks in the cog valleys cannot be sufficiently suppressed. Thus, since lateral pressure resistance and flexibility (cog valley crack resistance) are inversely related, it is effective to lower the elastic modulus (rigidity) of the compression rubber layer in order to suppress lateral pressure resistance and balance the two.

[0012] Methods for reducing the elastic modulus of a compression rubber layer include not incorporating short fibers into the rubber composition, reducing the amount of short fibers incorporated into the rubber composition, and changing the type of short fibers incorporated into the rubber composition to short fibers with a low elastic modulus. However, while these methods can reduce the elastic modulus of the compression rubber layer, they impair its resistance to lateral pressure and abrasion.

[0013] In particular, the size of the cog-equipped V-belt used in the power transmission mechanism (especially the belt-type continuously variable transmission) of the largest agricultural machinery disclosed in Patent Document 1 is very large, for example, equivalent to belts of the HL to HQ (designation as described in ISO 3410:1989) standard products of the American Society of Agricultural and Biotechnology Engineers (ASABE). In addition to standard products with belt widths (top widths) of 44.5 to 76.2 mm and belt thicknesses of 19.8 to 30.5 mm, ASABE also offers non-standard products with a belt thickness of 36 mm.

[0014] The large cog-equipped V-belts used in such large-scale power transmission mechanisms are belts applied on an even larger scale than those envisioned in Patent Document 2, and require a unique product design tailored to this application and operating environment. Therefore, simply adapting the design concept of Patent Document 2 is not applicable to the operating environment of the cog-equipped V-belt targeted by the present invention.

[0015] In other words, belt-type transmissions used in small-scale environments prioritize the ability to wrap around pulleys with small diameters, requiring a high degree of flexibility. On the other hand, belt-type transmissions used in large-scale environments require a moderate degree of flexibility while also ensuring high levels of lateral pressure resistance and transmission force to withstand the load levels of the power transmission mechanism. In particular, in large-scale environments, the lateral pressure from the pulleys becomes enormous, and a high level of rigidity (high modulus of elasticity) of the rubber layer is required to ensure sufficient lateral pressure resistance. Therefore, in belt-type transmissions (especially those used in large-scale environments), it is important to have a means to alleviate stress at the bottom of the cog valleys (including the deepest part of the cog valleys), where stress tends to concentrate due to bending deformation, while maintaining lateral pressure resistance and wear resistance, thereby ensuring resistance to cog valley cracking.

[0016] Therefore, the object of the present invention is to provide a cogged V-belt and its applications that can maintain resistance to lateral pressure and wear, and suppress the occurrence of cracks in the cog valleys and / or peeling of the core wires.

[0017] As a result of diligent research to achieve the above objectives, the inventors have found that by combining a first rubber layer on the inner circumference side of a cogged V-belt having cog portions in which cog peaks and cog valleys are alternately arranged in the longitudinal direction of the belt, with a second rubber layer on the outer circumference side of the belt that contains first short fibers and has a higher modulus of elasticity than the first rubber layer, it is possible to maintain lateral pressure resistance and abrasion resistance, and suppress the occurrence of cracks in the cog valleys and / or peeling of the core wires, thereby completing the present invention.

[0018] In other words, the present invention includes the following embodiments.

[0019] Embodiment [1]: A cogged V-belt having a cog portion on at least the inner circumference side in which cog peaks and cog valleys are alternately arranged in the longitudinal direction of the belt, wherein the cog portion comprises at least a compression rubber layer, the compression rubber layer includes a first rubber layer on the inner circumference side of the belt and a second rubber layer on the outer circumference side of the belt than the first rubber layer, the first rubber layer is formed of a first crosslinked rubber composition comprising a first rubber component and first short fibers, the second rubber layer is formed of a second crosslinked rubber composition comprising a second rubber component and second short fibers, the first rubber layer and the second rubber layer are exposed to form a friction transmission surface, and the elastic modulus of the first rubber layer is lower than the elastic modulus of the second rubber layer.

[0020] Embodiment [2]: The cog-equipped V-belt according to Embodiment [1], wherein, in a cross-sectional view in the thickness direction along the longitudinal direction of the belt, the area ratio of the first rubber layer is 30 to 80% of the total area of ​​the compression rubber layer.

[0021] Embodiment [3]: A cog-type V-belt according to Embodiment [1] or [2], wherein the modulus of elasticity of the second short fiber is higher than the modulus of elasticity of the first short fiber.

[0022] Embodiment [4]: ​​A cog-type V-belt according to any one of Embodiments [1] to [3], wherein the flexural modulus of the first rubber layer is 1.5 to 3 MPa and the flexural modulus of the second rubber layer is 2.5 to 4 MPa.

[0023] Embodiment [5]: A cog-type V-belt according to any one of Embodiments [1] to [4], wherein the proportion of the first short fibers is 15 to 35 parts by mass per 100 parts by mass of the first rubber component, and the proportion of the second short fibers is 10 to 30 parts by mass per 100 parts by mass of the second rubber component.

[0024] Embodiment [6]: A cog-type V-belt according to any of Embodiments [1] to [5], which is a low-edge cog-type V-belt.

[0025] Embodiment [7]: A belt transmission mechanism comprising a cog-equipped V-belt as described in any of Embodiments [1] to [6] and a pulley, and provided in a belt-type continuously variable transmission.

[0026] Aspect [8]: The belt transmission mechanism according to Aspect [7] provided in a belt-type continuously variable transmission in large agricultural machinery.

[0027] In the present application, the numerical range represented by "A to B" means "A or more and B or less" and is used in the sense of including the numerical values A and B at both ends.

[0028] In the present invention, the compression rubber layer of the cogged V-belt having at least on the inner peripheral side a cog portion in which cogs and cog valleys are alternately arranged in the belt longitudinal direction is a combination of a first rubber layer on the inner peripheral side of the belt containing first short fibers and a second rubber layer containing second short fibers, having a higher elastic modulus than the first rubber layer and on the outer peripheral side of the belt rather than the first rubber layer. Therefore, side pressure resistance and wear resistance can be maintained, and the occurrence of cracks in the cog valleys can be suppressed. Further, in the cogged V-belt of the present invention, the separation between the core wire and the rubber layer can also be suppressed.

[0029] FIG. 1 is a schematic cross-sectional view for explaining a speed change mechanism of a belt-type continuously variable transmission. FIG. 2 is a schematic partial cross-sectional perspective view showing an example of the cogged V-belt of the present invention. FIG. 3 is a schematic cross-sectional view obtained by cutting the cogged V-belt of FIG. 2 in the thickness direction along the belt longitudinal direction. FIG. 4 is a schematic perspective view for explaining a method of measuring the bending elastic modulus (short fiber parallel direction) of a crosslinked rubber molded body obtained in an example. FIG. 5 is a diagram showing the layout of a testing machine used in a deformation resistance test of a low-edge cogged V-belt obtained in an example.

[0030] [Structure of Cogged V-Belt] The cogged V-belt of the present invention has at least on the inner peripheral side a cog portion in which cogs and cog valleys are alternately arranged in the belt longitudinal direction, and the compression rubber layer forming the cog portion is multilayered, and the elastic modulus (rigidity) is adjusted with each rubber layer. Specifically, by increasing the elastic modulus of the rubber layer away from the cog valley, side pressure resistance and wear resistance can be maintained, and by reducing the elastic modulus of the rubber layer where the cog valley is located, the stress at the bottom of the cog valley can be relaxed. The elastic modulus of each rubber layer may be adjusted by a method of selecting the blending amount and type of each short fiber.

[0031] The cogged V-belt of the present invention is not particularly limited as long as the compression rubber layer forming the cog portion has the above structure, and may be a low-edge cogged V-belt in which cogs are formed only on the inner peripheral side of the low-edge V-belt, or may be a low-edge double-cogged V-belt in which cogs are formed on both the inner peripheral side and the outer peripheral side of the low-edge V-belt. Among these, the low-edge cogged V-belt is particularly preferable because it is widely used for large-sized transmission belts.

[0032] FIG. 2 is a schematic partial cross-sectional perspective view showing an example of the cogged V-belt (low-edge cogged V-belt) of the present invention, and FIG. 3 is a schematic cross-sectional view obtained by cutting the cogged V-belt of FIG. 2 in the thickness direction along the belt longitudinal direction.

[0033] In this example, the low-edge cogged V-belt 1 has a cog portion in which cog peaks 1a and cog valleys 1b are alternately arranged along the inner peripheral surface of the compression rubber layer 2 in the belt longitudinal direction (circumferential direction or direction A in the figure). The cross-sectional shape of the cog peak 1a in the thickness direction along the belt longitudinal direction is substantially trapezoidal in reverse (substantially trapezoidal in reverse in which the cog width decreases from the outer peripheral side to the inner peripheral side of the belt), and the cross-sectional shape of the cog peak 1a in the thickness direction along the direction orthogonal to the belt longitudinal direction (width direction or direction B in the figure) is substantially trapezoidal in reverse. That is, each cog peak 1a protrudes in a substantially trapezoidal shape in the cross-section in the A direction from the cog valley 1b in the belt thickness direction. That is, in the present invention, the top of the cog peak 1a is formed in a shape parallel to the belt longitudinal direction.

[0034] The low-edge cogged V-belt 1 has a laminated structure, and the compression rubber layer 2, the core layer (adhesive rubber layer) 3, and the extension rubber layer 5 are sequentially laminated from the inner peripheral side to the outer peripheral side of the belt. Further, a core wire 4 is embedded in the core layer 3, and the cog portion is formed in the compression rubber layer 2 by a cogged molding die.

[0035] In particular, in the present invention, the compression rubber layer 2 is formed of a first rubber layer 2a on the inner circumference side of the belt and a second rubber layer 2b on the outer circumference side of the belt than the first rubber layer 2a. In a cross-sectional view in the thickness direction along the circumferential direction of the belt (cross-sectional shape obtained by cutting in the thickness direction along the longitudinal direction of the belt), the boundary between the first rubber layer 2a and the second rubber layer 2b is a wave shape that follows the contours of the cog peaks 1a and cog valleys 1b (contours of the inner surface of the belt). In the compression rubber layer 2, a crosslinked rubber composition with a lower elastic modulus than the second rubber layer 2b is applied to the first rubber layer 2a, and the first rubber layer 2a is positioned at the bottom of the cog valleys 1b (including the deepest part of the cog valleys 1b) where stress tends to concentrate due to bending deformation. As a result, while maintaining lateral pressure resistance and abrasion resistance with the cross-linked rubber composition (high modulus) of the second rubber layer 2b (core wire side), the cross-linked rubber composition (low modulus) of the first rubber layer 2a is placed at the bottom of the cog valley 1b (including the deepest part of the cog valley) to relieve stress and suppress the occurrence of cracks in the cog valley.

[0036] [Compression Rubber Layer] In the cog-type V-belt of the present invention, the compression rubber layer includes a first rubber layer on the inner circumference side of the belt and a second rubber layer on the outer circumference side of the belt, relative to the first rubber layer.

[0037] (First rubber layer) The first rubber layer is formed of a first crosslinked rubber composition containing a first rubber component and first short fibers.

[0038] (1A) First rubber component The first rubber component may be a vulcanizable or crosslinkable rubber, for example, diene rubber [natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), hydrogenated nitrile rubber (H-NBR), etc.], ethylene-α-olefin elastomer [ethylene-propylene copolymer (EPM), ethylene-butene copolymer (EBM), ethylene-hexene copolymer (EHM), ethylene-octene copolymer (EOM), etc.] ３－８Olefin binary copolymers; ethylene-α-C such as ethylene-propylene-nonconjugated diene copolymer (EPDM), ethylene-1-butene-nonconjugated diene copolymer (EBDM), and ethylene-1-octene-nonconjugated diene copolymer (EODM). ３－８ Examples include olefin-non-conjugated polyene terpolymers, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, and fluororubber. These rubber components can be used individually or in combination of two or more.

[0039] Of these, ethylene-α-olefin elastomer and chloroprene rubber are preferred because they can improve durability such as ozone resistance, heat resistance, cold resistance, weather resistance, and crack resistance. ３－４ Ethylene-α-olefin-diene terpolymer rubber, such as olefin-non-conjugated diene terpolymer rubber, is preferred, and EPDM is particularly preferred.

[0040] When the first rubber component contains ethylene-α-olefin elastomer, the proportion of ethylene-α-olefin elastomer in the first rubber component may be 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more (particularly 90-100% by mass), and most preferably 100% by mass (ethylene-α-olefin elastomer only), from the viewpoint of improving the above properties and productivity.

[0041] The proportion of the first rubber component is 20 to 80% by mass, preferably 30 to 75% by mass, more preferably 40 to 70% by mass, more preferably 45 to 65% by mass, and most preferably 50 to 60% by mass in the first crosslinked rubber composition.

[0042] (1B) First staple fibers Examples of first staple fibers include polyamide staple fibers (aliphatic polyamide staple fibers such as polyamide 6 staple fibers, polyamide 66 staple fibers, polyamide 46 staple fibers, etc., aramid staple fibers, etc.), polyalkylene arylate staple fibers (e.g., polyethylene terephthalate (PET) staple fibers, polyethylene naphthalate staple fibers, etc.), liquid crystal polyester staple fibers, polyarylate staple fibers (amorphous all-aromatic polyester staple fibers, etc.), vinylon staple fibers, polyvinyl alcohol-based staple fibers, poly-p-phenylene benzobisoxazole (PBO) staple fibers, and other synthetic staple fibers; cellulose staple fibers such as cotton and linen, natural staple fibers such as wool; and inorganic staple fibers such as carbon staple fibers and glass staple fibers. These first staple fibers can be used alone or in combination of two or more types. Of these, short fibers with a low modulus of elasticity, such as aliphatic polyamide short fibers, polyalkylene arylate short fibers, and cellulose short fibers, are preferred because they make it easier to make the elastic modulus of the first rubber layer smaller than that of the second rubber layer, and aliphatic polyamide short fibers are particularly preferred because they make it easier to achieve the objectives of the present invention.

[0043] The first short fibers may be short fibers obtained by cutting fibers that have been stretched into a fibrous shape to a predetermined length. The first short fibers are preferably embedded in the first rubber layer oriented substantially parallel to the belt width direction in order to suppress compressive deformation of the belt due to lateral pressure from the pulley (to improve lateral pressure resistance). Furthermore, it is preferable to allow the short fibers to protrude from the surface of the first rubber layer in order to reduce wear due to friction with the pulley.

[0044] The average fiber length of the first short fibers is, for example, 0.1 to 20 mm, preferably 0.5 to 15 mm, more preferably 0.5 to 10 mm, more preferably 1 to 6 mm, and most preferably 2 to 4 mm, in order to improve lateral pressure resistance and abrasion resistance without reducing flexibility. If the fiber length of the first short fibers is too short, the mechanical properties in the direction of grain cannot be sufficiently improved, which may reduce lateral pressure resistance and abrasion resistance. If it is too long, the orientation of the first short fibers in the first crosslinked rubber composition may decrease, which may reduce flexibility.

[0045] The average fiber diameter of the first short fibers is, for example, 1 to 100 μm, preferably 3 to 70 μm, more preferably 5 to 50 μm, more preferably 10 to 40 μm, and most preferably 20 to 30 μm, in order to provide a high reinforcing effect without reducing flexibility. If the average fiber diameter is too small, the dispersibility in the rubber may decrease, which may reduce the flexibility of the belt. Conversely, if it is too large, the lateral pressure resistance and abrasion resistance of the belt per unit of compounding amount may decrease.

[0046] The average fineness of the first short fibers is, for example, 1 to 12 dtex, preferably 1.2 to 10 dtex, and more preferably 1.5 to 5 dtex.

[0047] The first short fibers may be embedded in the first rubber layer, oriented substantially parallel to the belt width direction, in order to suppress compressive deformation of the belt due to pressure from the pulley.

[0048] In this application, "approximately parallel" to the belt width direction means that the angle with respect to the belt width direction is, for example, 10° or less, preferably 8° or less, more preferably 5° or less, more preferably 3° or less, and most preferably 1° or less (for example, 0 to 1°, particularly approximately 0°).

[0049] The first short fibers may be subjected to conventional bonding treatments to enhance their adhesion to the first rubber component. Conventional bonding treatments include immersion in a treatment solution containing an epoxy compound or a polyisocyanate compound, immersion in an RFL treatment solution containing resorcinol (R), formaldehyde (F), and latex (L), and immersion in rubber adhesive. These treatments may be applied individually or in combination of two or more. Of these, immersion in an RFL treatment solution and immersion in rubber adhesive are preferred, and a combination of both methods is particularly preferred.

[0050] The proportion of the first short fibers is, for example, 10 to 50 parts by mass, preferably 15 to 35 parts by mass, more preferably 20 to 33 parts by mass, more preferably 22 to 32 parts by mass, and most preferably 25 to 30 parts by mass, per 100 parts by mass of the first rubber component. If there are too few first short fibers, the lateral pressure resistance and abrasion resistance of the belt may decrease, and if there are too many, the processability of the belt may decrease, or the flexibility of the belt may decrease, which may reduce its durability.

[0051] (1C) Other components The crosslinked rubber composition forming the first rubber layer may contain conventional additives (first additives), and the first additives include, for example, crosslinking agents or vulcanizing agents (sulfur-based crosslinking agents, organic peroxides, etc.), co-crosslinking agents (bismaleimides, etc.), crosslinking aids or crosslinking accelerators (thiuram-based accelerators, sulfenamide-based accelerators, thiomorpholine-based accelerators, etc.), crosslinking retarders, metal oxides (zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, copper oxide, titanium oxide, aluminum oxide, etc.), fillers [reinforcing agents such as carbon black, silicon oxide (hydrated silica, etc.) (reinforcing fillers); bulking agents such as clay, calcium carbonate, talc, mica (non-reinforcing fillers)] Examples of additives include: (or inert fillers), plasticizers (or softeners) [oils (paraffin oil and naphthenic oils, etc.), aliphatic carboxylic acid plasticizers, aromatic carboxylic acid ester plasticizers, oxycarboxylic acid ester plasticizers, phosphate ester plasticizers, ether plasticizers, ether ester plasticizers, etc.], processing agents or processing aids (stearic acid, metal stearic acid salts, waxes, paraffin, fatty acid amides, etc.), anti-aging agents (antioxidants, heat aging inhibitors, flex crack inhibitors, ozone degradation inhibitors, etc.), adhesion improvers, colorants, tackifiers, coupling agents (silane coupling agents, etc.), stabilizers (UV absorbers, heat stabilizers, etc.), flame retardants, antistatic agents, etc. These additives can be used individually or in combination of two or more. Metal oxides may also act as crosslinking agents.

[0052] The proportion of the crosslinking agent (first crosslinking agent) is, for example, 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, more preferably 0.7 to 2 parts by mass, and most preferably 0.8 to 1.5 parts by mass, per 100 parts by mass of the first rubber component.

[0053] The proportion of the crosslinking aid (first crosslinking aid) is, for example, 0.2 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 1 to 7 parts by mass, more preferably 2 to 6 parts by mass, and most preferably 3 to 5 parts by mass, per 100 parts by mass of the first rubber component.

[0054] The proportion of the filler (first filler) is, for example, 10 to 200 parts by mass, preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass, more preferably 30 to 70 parts by mass, and most preferably 40 to 60 parts by mass, per 100 parts by mass of the first rubber component. Carbon black is preferred as the first filler.

[0055] The proportion of the metal oxide (first metal oxide) is, for example, 0.5 to 30 parts by mass, preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass, per 100 parts by mass of the first rubber component. Zinc oxide is preferred as the first metal oxide.

[0056] The proportion of the plasticizer (first plasticizer) may be 20 parts by mass or less per 100 parts by mass of the first rubber component, for example, 0.1 to 20 parts by mass, preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass.

[0057] The proportion of the anti-aging agent (first anti-aging agent) is, for example, 0.2 to 10 parts by mass, preferably 0.5 to 8 parts by mass, more preferably 1 to 7 parts by mass, more preferably 2 to 6 parts by mass, and most preferably 3 to 5 parts by mass, per 100 parts by mass of the first rubber component.

[0058] The total proportion of the first additive is, for example, 5 to 300 parts by mass, preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and more preferably 50 to 100 parts by mass, per 100 parts by mass of the first rubber component.

[0059] (1D) Characteristics of the first rubber layer The elastic modulus of the first rubber layer (first crosslinked rubber composition) is lower than that of the second rubber layer (second crosslinked rubber composition). In this application, the elastic moduli of the first and second rubber layers are evaluated based on the flexural modulus (8% flexural modulus in the direction parallel to the short fibers) as an indicator of how easily the belt can be bent in the circumferential direction.

[0060] The flexural modulus of the first rubber layer (first crosslinked rubber composition) is, for example, 1.5 to 3 MPa (particularly 2 to 2.5 MPa), preferably 1.9 to 2.7 MPa, more preferably 2 to 2.6 MPa, even more preferably 2.1 to 2.6 MPa, and most preferably 2.2 to 2.5 MPa. If the flexural modulus is too low, the lateral pressure resistance of the belt may decrease, and conversely, if it is too high, the stress concentrated due to the bending deformation of the belt may not be relieved, and the crack resistance of the belt may decrease.

[0061] In this application, the flexural modulus is the 8% flexural modulus (or 8% flexural stress) in the direction parallel to the short fibers. Specifically, it can be measured by arranging the retaining member so that its longitudinal direction is the orientation direction (length direction) of the short fibers. More specifically, it can be measured by the method described in the embodiments below.

[0062] Furthermore, in this application, "direction parallel to the short fibers" may refer not only to the longitudinal direction of the short fibers, but also to directions within a range of ±5° from the longitudinal direction.

[0063] The area ratio of the first rubber layer is, for example, 10 to 90% (particularly 40 to 70%), preferably 30 to 80%, more preferably 40 to 75%, more preferably 50 to 70%, and most preferably 55 to 65% of the total area of ​​the compression rubber layer when viewed in a cross-sectional view in the thickness direction along the circumferential direction of the belt (cross-sectional shape obtained by cutting in the thickness direction along the longitudinal direction of the belt). If the area ratio is too small, the crack resistance of the belt may decrease, and if it is too large, the lateral pressure resistance of the belt may decrease.

[0064] In this application, the area ratio of each rubber layer in the compressed rubber layer is considered to be the ratio calculated from the thickness ratio of the raw material, the uncrosslinked rubber sheet.

[0065] The shape of the first rubber layer is not particularly limited as long as it is located on the inner circumference side relative to the second rubber layer and has the aforementioned area ratio. As shown in Figures 2 and 3, the interface with the second rubber layer may be a layer shape along the inner surface of the belt (the boundary with the second rubber layer is wavy in the cross-section in the thickness direction along the longitudinal direction of the belt), or the interface may be a layer shape along the flat outer surface of the cogted V-belt shown in Figure 2 (the boundary with the second rubber layer is straight in the cross-section in the thickness direction along the longitudinal direction of the belt).

[0066] The average thickness of the first rubber layer is, for example, 1 to 15 mm, preferably 3 to 10 mm, more preferably 4 to 9 mm, more preferably 5 to 8 mm, and most preferably 6 to 8 mm. If the average thickness is too thin, the crack resistance of the belt may decrease, and if it is too thick, the lateral pressure resistance of the belt may decrease.

[0067] In this application, the average thickness of the first rubber layer is the sum of the thickness measured at the center of each cog peak and the thickness measured at the center of each cog valley, divided by 10.

[0068] (Second rubber layer) The second rubber layer is formed of a second crosslinked rubber composition containing a second rubber component and second short fibers.

[0069] (2A) Second rubber component The second rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The second rubber component may be a different rubber component from the first rubber component, but is usually the same rubber component as the first rubber component.

[0070] The proportion of the second rubber component in the second crosslinked rubber composition can be selected from the proportion of the first rubber component in the first crosslinked rubber composition, including a preferred range.

[0071] (2B) Second short fibers Examples of the second short fibers include the short fibers exemplified as the first short fibers. The short fibers can be used alone or in combination of two or more types. Among the short fibers, high modulus short fibers such as aramid short fibers and PBO short fibers are preferred as the second short fibers, as they make it easier to make the modulus of elasticity of the second rubber layer greater than that of the first rubber layer and thus easier to achieve the objectives of the present invention. In particular, in the present invention, it is preferable that the modulus of elasticity of the second short fibers is higher than that of the first short fibers.

[0072] The second short fiber may be a short fiber obtained by cutting a fibrously stretched fiber to a predetermined length. The second short fiber is preferably embedded in the second rubber layer oriented substantially parallel to the belt width direction in order to suppress compressive deformation of the belt due to lateral pressure from the pulley. Furthermore, it is preferable to have the short fiber protrude from the surface of the second rubber layer in order to reduce wear due to friction with the pulley.

[0073] The average fiber length of the second short fibers is, for example, 0.1 to 20 mm, preferably 0.5 to 15 mm, more preferably 0.5 to 10 mm, more preferably 1 to 6 mm, and most preferably 2 to 4 mm, in order to improve lateral pressure resistance and abrasion resistance without reducing flexibility. If the fiber length of the second short fibers is too short, the mechanical properties in the direction of grain cannot be sufficiently improved, which may reduce lateral pressure resistance and abrasion resistance. Conversely, if the fiber length is too long, the orientation of the second short fibers in the crosslinked rubber composition may decrease, which may reduce flexibility.

[0074] The average fineness of the second short fibers is, for example, 1 to 12 dtex, preferably 1.2 to 10 dtex, more preferably 1.5 to 5 dtex, more preferably 1.8 to 3 dtex, and most preferably 2 to 2.5 dtex, in order to provide a high reinforcing effect without reducing flexibility. If the average fineness is too small, the flexibility of the belt may decrease due to reduced dispersibility in the rubber, and conversely, if it is too large, the lateral pressure resistance and abrasion resistance of the belt per unit amount may decrease.

[0075] The average fiber diameter of the second short fiber is, for example, 1 to 100 μm, preferably 3 to 70 μm, more preferably 5 to 50 μm, more preferably 7 to 40 μm, and most preferably 10 to 30 μm.

[0076] The second short fibers may be embedded in the second rubber layer, oriented substantially parallel to the belt width direction, in order to suppress compressive deformation of the belt due to pressure from the pulley.

[0077] The second short fiber may be subjected to a conventional bonding treatment to enhance its adhesion to the second rubber component. The conventional bonding treatment can be selected from the bonding treatments exemplified as bonding treatments for the first short fiber, including preferred embodiments.

[0078] The proportion of the second short fibers is, for example, 5 to 50 parts by mass (particularly 10 to 30 parts by mass), preferably 13 to 29 parts by mass, more preferably 15 to 28 parts by mass, more preferably 18 to 27 parts by mass, and most preferably 20 to 25 parts by mass, per 100 parts by mass of the second rubber component. If there are too few second short fibers, the lateral pressure resistance and abrasion resistance of the belt may decrease, and conversely, if there are too many, the processability of the belt may decrease, or the flexibility of the belt may decrease, which may reduce its durability.

[0079] (2C) Other components The second crosslinked rubber composition forming the second rubber layer may contain conventional additives (second additives), and the second additive can be selected from the additives exemplified as first additives, including preferred embodiments. The ratio of each second additive to 100 parts by mass of the second rubber component can also be selected from the ratio of each first additive to 100 parts by mass of the first rubber component, including a preferred range. The total ratio of the second additives to 100 parts by mass of the second rubber component can also be selected from the total ratio of the first additives to 100 parts by mass of the first rubber component, including a preferred range.

[0080] (2D) Characteristics of the second rubber layer The flexural modulus of the second rubber layer (second crosslinked rubber composition) is, for example, 2.5 to 4 MPa (particularly 3.1 to 3.4 MPa), preferably 2.9 to 3.5 MPa, more preferably 3 to 3.3 MPa, even more preferably 3.1 to 3.3 MPa, and most preferably 3.2 to 3.3 MPa. If the flexural modulus is too low, the lateral pressure resistance of the belt may decrease, and conversely, if it is too high, the flexibility of the belt may decrease.

[0081] The second rubber layer may have a structure in which multiple rubber layers with different flexural moduli are laminated, but a single-layer structure is preferred from the standpoint of productivity and other factors.

[0082] The area ratio of the second rubber layer is, in a cross-sectional view in the thickness direction along the circumferential direction of the belt, for example, 10 to 90% (particularly 10 to 70%), preferably 15 to 60%, more preferably 20 to 55%, more preferably 30 to 50%, and most preferably 35 to 45% of the total area of ​​the compression rubber layer. If the area ratio is too small, the lateral pressure resistance of the belt may decrease, and conversely, if it is too large, the crack resistance of the belt may decrease.

[0083] The shape of the second rubber layer is not particularly limited as long as it is interposed between the first rubber layer and the core layer and has the aforementioned area ratio. As shown in Figures 2 and 3, the interface with the first rubber layer may be a layer shape along the inner surface of the belt (the boundary with the first rubber layer is wavy in the cross-section in the thickness direction along the longitudinal direction of the belt), or the interface may be a layer shape along the flat outer surface of the belt (the boundary with the first rubber layer is linear in the cross-section in the thickness direction along the longitudinal direction of the belt).

[0084] The average thickness of the second rubber layer is, for example, 1 to 12 mm, preferably 1.5 to 10 mm, more preferably 2 to 9 mm, more preferably 3 to 8 mm, and most preferably 4 to 6 mm. If the average thickness is too thin, the lateral pressure resistance of the belt may decrease, and conversely, if it is too thick, the flexibility of the belt may decrease.

[0085] In this application, the average thickness of the second rubber layer is the sum of the thickness measured at the center of each cog peak and the thickness measured at the center of each cog valley, divided by 10.

[0086] (Characteristics of the Compressed Rubber Layer) The flexural modulus of the first rubber layer may be 0.5 to 0.9 times that of the flexural modulus of the second rubber layer, preferably 0.6 to 0.8 times, more preferably 0.62 to 0.8 times, more preferably 0.63 to 0.75 times, and most preferably 0.65 to 0.7 times. If the ratio of the flexural modulus of the first rubber layer is too small, the crack resistance of the belt may decrease, and if it is too large, the lateral pressure resistance of the belt may decrease.

[0087] The compression rubber layer may further include other rubber layers in addition to the first and second rubber layers, as long as it does not impair the effects of the present invention. The other rubber layer may be an adhesive rubber layer (first adhesive rubber layer) interposed between the reinforcing fabric and the first rubber layer when the inner circumferential surface of the cog portion is covered with the reinforcing fabric. The thickness of the first adhesive rubber layer should be such that it improves the adhesion between the reinforcing fabric and the first rubber layer. The average thickness of the first adhesive rubber layer is preferably 0.5 mm or less, and more preferably 0.3 mm or less. If the thickness of the first adhesive rubber layer is too thick, the lateral pressure resistance of the belt may decrease.

[0088] The preferred structure of the compression rubber layer is one consisting of a first rubber layer on the inner circumference of the belt and a second rubber layer on the outer circumference of the belt.

[0089] The average thickness of the compression rubber layer is, for example, 5 to 30 mm, preferably 10 to 25 mm, more preferably 12 to 20 mm, and more preferably 15 to 18 mm. In this application, the thickness of the compression rubber layer refers to the maximum thickness (thickness at the top of the cog portion).

[0090] [Core Layer] The core layer only needs to include a core wire as the core, and may be a core layer formed only of core wires. However, a combination of a core wire and an adhesive rubber layer (third adhesive rubber layer) formed of a third crosslinked rubber composition containing a third rubber component is preferred in order to suppress delamination between layers and improve belt durability. When forming a core layer by combining a core wire and a third adhesive rubber layer, at least a part of the core wire needs to be in contact with the third adhesive rubber layer, and it may be in any of the following forms: the third adhesive rubber layer embeds the core wire, the core wire is embedded between the third adhesive rubber layer and the stretch rubber layer, or the core wire is embedded between the third adhesive rubber layer and the compression rubber layer. Of these, the form in which the third adhesive rubber layer embeds the core wire is preferred in order to improve durability (i.e., the third adhesive rubber layer is interposed between the stretch rubber layer and the compression rubber layer to bond the stretch rubber layer and the compression rubber layer, and the entire core wire is embedded in the third adhesive rubber layer).

[0091] (Third adhesive rubber layer) The third adhesive rubber layer is formed of a third crosslinked rubber composition containing a third rubber component.

[0092] (3A) Third rubber component The third rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The third rubber component may be a different rubber component from the first rubber component, but is usually the same rubber component as the first rubber component.

[0093] (3B) Other components The third adhesive rubber layer may contain conventional additives (third additives). Examples of third additives include those exemplified as first additives. These additives can be used alone or in combination of two or more.

[0094] The proportion of the third crosslinking agent is, for example, 0.1 to 10 parts by mass, preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, more preferably 0.7 to 2 parts by mass, and most preferably 0.8 to 1.5 parts by mass, per 100 parts by mass of the third rubber component.

[0095] The proportion of the third crosslinking aid is, for example, 0.2 to 10 parts by mass, preferably 0.3 to 7 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, and most preferably 1.5 to 2.5 parts by mass, per 100 parts by mass of the third rubber component.

[0096] The proportion of the third filler is, for example, 10 to 200 parts by mass, preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass, more preferably 30 to 70 parts by mass, and most preferably 40 to 60 parts by mass, per 100 parts by mass of the third rubber component. A combination of carbon black and silica is preferred as the third filler.

[0097] The proportion of the third metal oxide is, for example, 0.5 to 30 parts by mass, preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass, per 100 parts by mass of the third rubber component. Zinc oxide is preferred as the third metal oxide.

[0098] The proportion of the third plasticizer may be 20 parts by mass or less (particularly 10 parts by mass or less) per 100 parts by mass of the third rubber component, for example, 0.1 to 20 parts by mass, preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, more preferably 3 to 7 parts by mass, and most preferably 4 to 6 parts by mass.

[0099] The proportion of the third anti-aging agent is, for example, 0.2 to 10 parts by mass, preferably 0.3 to 7 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 1 to 3 parts by mass, and most preferably 1.5 to 2.5 parts by mass, per 100 parts by mass of the third rubber component.

[0100] The total proportion of the third additive is, for example, 5 to 300 parts by mass, preferably 10 to 200 parts by mass, more preferably 30 to 150 parts by mass, and more preferably 50 to 100 parts by mass, per 100 parts by mass of the third rubber component.

[0101] The third adhesive rubber layer may contain short fibers (third short fibers). The third short fibers can be selected from the short fibers exemplified as the first short fibers, including preferred embodiments.

[0102] The proportion of the third short fibers is, for example, 50 parts by mass or less, preferably 30 parts by mass or less, more preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and most preferably 1 part by mass or less, per 100 parts by mass of the third rubber component. The third adhesive rubber layer does not need to contain short fibers.

[0103] The average thickness of the third adhesive rubber layer is, for example, 0.8 to 5 mm, preferably 1.5 to 4 mm, more preferably 2 to 3.5 mm, and more preferably 2.5 to 3 mm.

[0104] (Core wire) The core wire is not particularly limited, but typically, core wires (twisted cords) arranged at predetermined intervals in the belt width direction can be used. The core wires may be embedded at equal intervals (or pitches) from one end to the other in the belt width direction of the core layer.

[0105] The core wires are arranged extending in the longitudinal direction (circumferential direction) of the belt, and multiple core wires may be arranged parallel to the longitudinal direction of the belt. However, from the standpoint of productivity, they are usually arranged spirally, extending in parallel at a predetermined pitch, approximately parallel to the longitudinal direction of the cogted V-belt. When arranged spirally, the angle of the core wires with respect to the longitudinal direction of the belt may be, for example, 5° or less, and from the standpoint of belt running performance, it is preferable that the angle is as close to 0° as possible.

[0106] The core wire pitch (the distance between the centers of adjacent core wires) should be greater than the core wire diameter and is set in the range of approximately 0.5 to 3.5 mm depending on the core wire diameter, preferably 1.5 to 3 mm, more preferably 2 to 2.5 mm, and more preferably 2.2 to 2.4 mm.

[0107] Examples of fibers constituting the core wire include those exemplified as fibers constituting the first short fibers. Among these fibers, synthetic fibers such as polyester fibers (polyalkylene arylate fibers) and aramid fibers, and inorganic fibers such as carbon fibers are often used from the viewpoint of high modulus, with polyalkylene arylate fibers and aramid fibers being preferred, and aramid fibers being particularly preferred.

[0108] The fiber may be a multifilament yarn. The fineness of the multifilament yarn is, for example, 300 to 10,000 dtex, preferably 500 to 5,000 dtex, and more preferably 1,000 to 3,000 dtex. The multifilament yarn may contain, for example, about 100 to 5,000 monofilament yarns, preferably 500 to 4,000 monofilament yarns, and more preferably about 1,000 to 3,000 monofilament yarns.

[0109] Typically, twisted cords using multifilament yarn (e.g., multi-ply, single-ply, Lang-ply, etc.) can be used as the core wire. The average wire diameter of the core wire (diameter of the twisted cord) may be, for example, 0.5 to 3 mm, preferably 1 to 2.5 mm, more preferably 1.5 to 2.3 mm, more preferably 1.7 to 2.1 mm, and most preferably 1.8 to 2 mm. If the core wire is too thin, the flexibility will improve, but the tension of the belt may decrease, and conversely, if it is too thick, the bending resistance of the belt may decrease.

[0110] The core wire may be bonded (or surface-treated) in the same manner as the first short fiber in order to improve its adhesion to the third rubber component. Preferably, the core wire is bonded with at least RFL liquid.

[0111] [Stretchable Rubber Layer] The stretchable rubber layer is formed of a fourth crosslinked rubber composition containing a fourth rubber component.

[0112] The fourth rubber component can be selected from the rubber components exemplified as the first rubber component, including preferred embodiments. The fourth rubber component may be a different rubber component from the first rubber component, but is usually the same rubber component as the first rubber component.

[0113] The fourth crosslinked rubber composition forming the stretchable rubber layer also preferably contains fourth short fibers, as this further improves lateral pressure resistance and abrasion resistance. Including fourth short fibers as short fibers not only in the compression rubber layer but also in the stretchable rubber layer further improves lateral pressure resistance and abrasion resistance. The fourth short fibers can be selected from the short fibers exemplified in the second short fibers, including preferred embodiments. The fourth short fibers may be different from the second short fibers, but are usually the same as the second short fibers. The proportion of the fourth short fibers can be selected from the proportion of the second short fibers, including preferred proportions.

[0114] The rubber composition forming the stretchable rubber layer may further contain other components as exemplified in the second crosslinked rubber composition forming the second rubber layer of the compression rubber layer.

[0115] The average thickness of the stretched rubber layer is, for example, 0.5 to 3 mm, preferably 0.8 to 2.5 mm, and more preferably 1.1 to 2.2 mm.

[0116] [Reinforcement Fabric] The cog-equipped V-belt of the present invention may include a reinforcement fabric. Examples of the form of the reinforcement fabric include lamination on the surface of the stretchable rubber layer and / or the compression rubber layer, and embedding in the stretchable rubber layer and / or the compression rubber layer (for example, the form described in Japanese Patent Publication No. 2010-230146).

[0117] The reinforcing fabric may be made of conventional fabrics. Examples of conventional fabrics include woven fabrics, knitted fabrics (weft knitted fabrics, warp knitted fabrics), and nonwoven fabrics. Of these, woven fabrics such as plain weave, twill weave, and satin weave, and woven or knitted fabrics with intersection angles exceeding 90° and not exceeding 120° are preferred. Woven fabrics commonly used as cover fabrics for transmission belts in general industrial and agricultural machinery [plain weave fabrics with right-angle intersections, and plain weave fabrics with intersection angles exceeding 90° and not exceeding 120° (wide-angle canvas)] are particularly preferred. Furthermore, in applications where durability is required, the fabric may be wide-angle canvas.

[0118] Examples of fibers constituting the fabric include the fibers exemplified as constituting the first short fibers of the first rubber layer. The fibers may be single yarns using only one type of fiber, or composite yarns (such as blended yarns) combining two or more types of fibers. Among the fibers, polyalkylene arylate short fibers and cellulose short fibers are preferred.

[0119] The reinforcing fabric may be treated with adhesive, for example, with RFL liquid (such as immersion treatment), or with friction treatment by rubbing adhesive rubber onto the fabric, or the adhesive rubber and the fabric may be laminated together and then laminated or embedded in the stretch rubber layer and / or compression rubber layer in a laminated form.

[0120] The average thickness of the reinforcing fabric is, for example, 0.1 to 1.5 mm, preferably 0.2 to 1 mm, and more preferably 0.3 to 0.7 mm.

[0121] [Characteristics of Cog V-Belts] The cog V-belt of the present invention is not particularly limited as long as it has cog portions on at least the inner circumference side in which cog peaks and cog valleys are alternately arranged in the longitudinal direction of the belt, and the first rubber layer and the second rubber layer constituting the compression rubber layer are exposed to form a friction transmission surface. Examples of such cog V-belts include low-edge V-belts (low-edge cogded V-belts) in which cogs are formed only on the inner circumference side, and low-edge double cogded V-belts in which cogs are formed on both the inner and outer circumference sides. Of these, low-edge cogded V-belts are preferred.

[0122] The overall thickness H of the cog-type V-belt of the present invention is 8 mm or more, for example, 8 to 36 mm, preferably 13 to 33 mm, more preferably 15 to 30 mm, and more preferably 18 mm or more and less than 27 mm. In particular, the cog-type V-belt of the present invention is preferably a speed-shifting belt used in a large belt-type continuously variable transmission, with an overall thickness of 18 mm or more.

[0123] In this application, the overall thickness of a cog-type V-belt refers to the thickness from the outer circumferential surface to the inner circumferential surface (the thickness at the thickest point of the belt), and in the cog portion, the top of the cog is either the inner or outer circumferential surface. Therefore, in a low-edge cog-type V-belt that has cogs only on the inner circumferential surface, the distance from the outer circumferential surface to the top of the cog portion on the inner circumferential surface is the overall thickness. In other words, in the case of a low-edge cog-type V-belt, the overall thickness refers to the distance from the top of the cog in the compression rubber layer (the convex top on the inner circumferential side) to the back of the belt, and in the case of a low-edge double-cog-type V-belt, it refers to the distance from the top of the cog in the compression rubber layer (the convex top on the inner circumferential side) to the top of the cog in the stretch rubber layer (the convex top on the outer circumferential side).

[0124] The height of the cog portion (cog height) of the cog portion of the V-belt with cogs of the present invention (cog height) H １ The shortest distance (in the belt thickness direction, from the deepest part of the cog valley to the top of the cog) is, for example, 5 to 20 mm, preferably 10 to 15 mm, more preferably 11 to 14 mm, and more preferably 12 to 13 mm. Cog height H １ If the value is too low, the belt's flexibility may decrease, and if it is too high, the belt's durability may decrease.

[0125] The thickness of the valley portion (center valley thickness) of the cogted V-belt of the present invention H ２ The shortest distance (in the belt thickness direction, from the central axis of the core wire to the deepest part of the cog valley) is, for example, 0.5 to 15 mm, preferably 1 to 13 mm, more preferably 2 to 11 mm, more preferably 3 to 8 mm, and most preferably 4 to 7 mm. Core valley thickness H ２ If the material is too thin, the belt's durability may decrease, and if it is too thick, the belt's flexibility may decrease.

[0126] [Method for Manufacturing Cogged V-Belts] The method for manufacturing cogged V-belts of the present invention is not particularly limited, and conventional methods can be used for the lamination process of each layer (method for manufacturing the belt sleeve) depending on the type of belt. Below, two representative methods for manufacturing raw-edge cogged V-belts will be described.

[0127] (First manufacturing method) When manufacturing a low-edge cogged V-belt in which a cog portion is formed at least on the inner circumference side of the belt, a cylindrical mold such as a cogged mold can be used, in which a surface with irregularities corresponding to the cog shape is engraved on the outer surface of the cylinder.

[0128] First, a laminate of an uncrosslinked sheet for the first rubber layer and an uncrosslinked sheet for the second rubber layer is placed with the uncrosslinked sheet for the first rubber layer facing downwards, in contact with a flat cog mold having teeth and grooves arranged alternately to correspond to the inner circumference cog portion. A cog pad (a pad that is not completely crosslinked, but in a semi-crosslinked state) is then produced by pressing it at a temperature of 60 to 120°C (especially 80 to 100°C) to form the inner circumference cog portion. Then, both ends of this cog pad are cut vertically at appropriate points (especially the tops of the cog peaks) to obtain the required length.

[0129] Next, an inner mold having teeth and grooves arranged alternately to correspond to the inner cog portion is placed over the outer circumference of the cylindrical mold (cog mold), and the cog pad is wrapped around it by engaging with the teeth and grooves of the inner mold and joined at both ends (especially the tops of the cog peaks). An uncrosslinked sheet for the first adhesive rubber layer (lower adhesive rubber) is wrapped around the outer circumference of the cog pad and laminated, and then a core wire (twisted cord) that will become the core body is spun in a spiral shape, and an uncrosslinked sheet for the second adhesive rubber layer (upper adhesive rubber), which is the same as the uncrosslinked sheet for the first adhesive rubber layer, an uncrosslinked sheet for the stretch rubber layer, and a reinforcing fabric precursor for the outer circumference are wrapped around its outer circumference in this order to obtain an uncrosslinked laminate.

[0130] Subsequently, the mold with the laminate attached is placed in a known crosslinking device (such as a vulcanizing can) with a jacket covering the outer circumference of the laminate, and crosslinking is performed at a temperature of approximately 120 to 200°C (especially 150 to 180°C). This causes the rubber components of each rubber layer to crosslink and the laminate to bond and integrate, thereby preparing a belt sleeve (crosslinked sleeve) with a cog portion formed on the inner circumference. The obtained crosslinked sleeve is cut to a predetermined width using a cutter or the like, and the sides are further cut into a V-shape to obtain a predetermined V-angle, thereby forming a low-edge cogged V-belt with a cog portion formed on the inner circumference.

[0131] Furthermore, an uncrosslinked laminate can be obtained without using an uncrosslinked sheet for the second adhesive rubber layer. Also, when the adhesive rubber layer is formed with multiple uncrosslinked sheets for the adhesive rubber layer, the core wire can be spun in relation to the lamination order of the multiple adhesive rubber layer sheets, depending on the embedding position in the adhesive rubber layer.

[0132] Furthermore, as a means of forming the cog portion, as described in Japanese Patent Publication No. 2018-35939, a belt sleeve (bridged sleeve) without a cog portion formed on its inner circumferential surface may be prepared using a flat cylindrical mold without engraved uneven surfaces corresponding to the cog shape, and then the cog portion may be formed by removing the material from the bridged sleeve using a cutting tool or a water jet machine.

[0133] (Second manufacturing method) Using a flat cylindrical mold without any grooves or uneven surfaces corresponding to the cog shape as the mold, the reinforcing fabric precursor, the uncrosslinked sheet for the stretchable rubber layer, the uncrosslinked sheet for the second adhesive rubber layer (upper adhesive rubber), the core wire, the uncrosslinked sheet for the first adhesive rubber layer (lower adhesive rubber), and the cog pad are wound in the reverse order of the first manufacturing method to obtain an uncrosslinked laminate.

[0134] A cylindrical rubber mold with an uneven surface corresponding to the cog shape formed on its inner surface is placed over the outer circumference of the laminate. Then, with the jacket placed over the outer circumference of the rubber mold, it is placed in a vulcanizing apparatus and cross-linked molding is performed at a temperature of approximately 120 to 200°C (especially 150 to 180°C) to prepare a belt sleeve (cross-linked sleeve) with a cog shape formed on its outer circumference. The obtained cross-linked sleeve is cut to a predetermined width using a cutter or the like, and then the sides are cut into a V shape to obtain a predetermined V angle. Finally, the outer and inner circumferences are reversed to obtain a low-edge cogged V belt with a cog portion formed on the inner circumference.

[0135] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. Details of the materials used in the examples, the method for producing the uncrosslinked rubber sheet, and the methods for measuring or evaluating each physical property are shown below.

[0136] [Materials Used] EPDM: NORDEL® IP4640 manufactured by DowDuPont, ethylene content 55% by mass, ethylidene norbornene content 4.9% by mass Aramid staple fibers: Twaron® manufactured by Teijin Limited, modulus 88 cN, fineness 2.2 dtex, fiber length 3 mm Nylon staple fibers: Leona® manufactured by Asahi Kasei Corporation, average fiber diameter 27 μm, average fiber length 3 mm PET staple fibers: Koyu Staple Fiber Co., Ltd., average fiber diameter 17 μm, average fiber length 3 mm Cotton staple fibers: Cotton staple fibers manufactured by Hashimoto Co., Ltd., average fineness (cotton count) 8 count, average fiber length 6 mm PBO staple fibers: Zylon® manufactured by Toyobo Co., Ltd., average fiber diameter 12 μm, average fiber length 3 mm Naphthenic oil: "Diana® Process Oil NS-90S" manufactured by Idemitsu Kosan Co., Ltd. Silica: "ULTRASIL® VN3" manufactured by Evonik Japan Co., Ltd., BET specific surface area 175 m² ２ / g Carbon black HAF: "Seist® 3" manufactured by Tokai Carbon Co., Ltd. Zinc oxide: "Zinc Oxide 3 types" manufactured by Seido Chemical Industry Co., Ltd. Anti-aging agent: "Nocrack® AD-F" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Crosslinking accelerator DM: Dibenzothiadyl disulfide, "Noxella® DM" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Crosslinking accelerator TT: Tetramethylthiuram disulfide, "Noxella® TT" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Crosslinking accelerator CZ: N-cyclohexyl-2-benzothiadylsulfenamide, "Noxella® CZ" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Sulfur: "Sulfur" manufactured by Bigen Chemical Co., Ltd.

[0137] [Core wire] Two strands of aramid fiber multifilament yarn (fineness 1,680 dtex) were held together and under-twisted. Three of these were then combined and over-twisted in the opposite direction to the under-twist to create a multi-twist cord with a total fineness of 10,080 dtex (average wire diameter 1.81 mm). This cord was then further treated with adhesive to prepare the finished cord.

[0138] [Preparation of Unvulcanized Rubber Sheet for Rubber Layer] The rubber compositions for forming the compression rubber layer, the extension rubber layer, and the adhesive rubber layer were prepared at the compounding ratios shown in Table 1. Each rubber composition for forming a layer was kneaded using a Banbury mixer, and the obtained kneaded rubber was passed through calender rolls to produce a rolled rubber sheet (unvulcanized rubber sheet). In this specification, each rubber composition is denoted by R1 to R15.

[0139]

[0140] [Reinforcing Fabric] A woven fabric of a blended yarn of polyester fiber and cotton (polyester fiber / cotton = 50 / 50 mass ratio) (120° wide-angle weaving, the fineness is 20-count warp and 20-count weft, the yarn density of warp and weft is 75 threads / 50 mm, and the basis weight is 280 g / m ２ ) was coated by a method of simultaneously passing through calender rolls together with the previously kneaded rubber composition R15 to laminate and adhere the rubber composition R15 to the woven fabric, thereby preparing a reinforcing fabric precursor.

[0141] [Flexural Modulus] An uncrosslinked rubber composition having the composition shown in Table 1 was press-heated at a temperature of 160°C and a pressure of 2 MPa for 20 minutes to produce a crosslinked rubber molded body (60 mm × 25 mm × 6.5 mm thick). The short fibers were oriented perpendicular to the longitudinal direction of the crosslinked rubber molded body. As shown in Figure 4, the crosslinked rubber molded body 21 was supported on a pair of rotatable rolls (6 mm in diameter) 22a and 22b spaced 20 mm apart, and a metal pressing member 23 was placed on the center of the upper surface of the crosslinked rubber molded body in the width direction (parallel to the orientation direction of the short fibers). The tip of the pressing member 23 has a semicircular shape with a diameter of 10 mm, and the crosslinked rubber molded body 21 can be smoothly pressed with its tip. Furthermore, during pressing, a frictional force acts between the lower surface of the cross-linked rubber molded body 21 and the rolls 22a and 22b due to the compressive deformation of the cross-linked rubber molded body 21. However, by making the rolls 22a and 22b rotatable, the effect of friction is reduced. The initial position was set with the tip of the pressing member 23 in contact with the upper surface of the cross-linked rubber molded body 21 and not pressing. From this position, the pressing member 23 was pressed downwards at a speed of 100 mm / min against the upper surface of the cross-linked rubber molded body 21, and the flexural modulus at a bending strain of 8% was measured. The measurement temperature was set to 120°C, assuming the belt temperature during operation. The smaller the flexural modulus in the direction parallel to the short fibers (8% flexural modulus), the better the flexibility of the belt can be judged, with 1.5 to 3 MPa being considered good.

[0142] [Area ratio of the first rubber layer] The area ratio of the first rubber layer refers to the ratio to the total area of ​​the compression rubber layer in a cross-sectional view along the thickness direction in the circumferential direction of the belt. The thickness of the uncrosslinked rubber sheet for the first rubber layer is considered to be the area ratio of the first rubber layer to the total thickness of the uncrosslinked rubber sheet for the first rubber layer and the uncrosslinked rubber sheet for the second rubber layer.

[0143] [Deformation Resistance Test] The deformation resistance test was conducted using a two-axis running test machine with a layout consisting of a drive (Dr.) pulley and a driven (Dn.) pulley, as shown in Figure 5. The pitch diameter of the drive pulley, the pitch diameter of the driven pulley, and the distance between the axes were adjusted to the values ​​shown in Table 2 so that the gear ratio remained constant even if the overall thickness of the belt differed. A raw edge cogged V-belt was mounted on these two pulleys, and the axial load was set to 15,000 N, the rotation speed of the drive pulley to 1,398 rpm, and the rotation speed of the driven pulley under no load to 2,419 rpm. The belt was run for 30 minutes at an ambient temperature of 25°C. A high load of 400 kW was applied to the driven pulley for a short time, and the surface temperature of the belt during running was measured with a non-contact thermometer and judged according to the following criteria. The deformation referred to is buckling deformation called dishing during belt operation. Since a large buckling deformation causes the belt temperature to rise, the belt surface temperature was used as an indicator of deformation resistance, and a belt surface temperature of 165°C or lower was considered an acceptable level for deformation resistance.

[0144]

[0145] (Judgment Criteria) a: Belt temperature 125°C or less (Pass) b: Belt temperature exceeding 125°C but 145°C or less (Pass) c: Belt temperature exceeding 145°C but 165°C or less (Pass) d: Belt temperature exceeding 165°C (Fail)

[0146] [Wear Resistance Test] In the deformation resistance test method described above, the load applied to the driven pulley was set to 160 kW, and the belt was run for 150 hours at an ambient temperature of 25°C. The upper width of the belt was measured before and after running, and judged according to the following criteria. The change in upper width before and after running (wear loss) was used as an indicator of wear resistance, and a change in upper width of 1.0 mm or less was considered a passing level for wear resistance.

[0147] (Judgment Criteria) a: Change in upper width (wear loss) is 0.6 mm or less (Pass) b: Change in upper width (wear loss) is greater than 0.6 mm but 0.8 mm or less (Pass) c: Change in upper width (wear loss) is greater than 0.8 mm but 1.0 mm or less (Pass) d: Change in upper width (wear loss) is greater than 1.0 mm (Fail)

[0148] [Cog Valley Crack Resistance Test] Using the same method as the abrasion resistance test described above, the side surface of the belt was visually inspected after running the belt for 150 hours to check for delamination between the adhesive rubber layer and the core wire, and for the presence of cracks in the cog valleys. The results were then judged according to the following criteria.

[0149] (Judgment Criteria) a: No cracks or peeling were observed at all (Pass) b: Some cracks or peeling were observed (Pass) c: Cracks or peeling were minor (not affecting the belt's performance) (Pass) d: Cracks or peeling occurred to an extent that affected the belt's performance (Fail)

[0150] [Overall Assessment] The criteria for the overall assessment (ranking) of a cog-type V-belt capable of solving this problem were determined based on the results of the assessments in the three evaluation items above (deformation resistance, wear resistance, and cog valley crack resistance), according to the criteria shown in Table 3, with a rank of C or higher being considered acceptable.

[0151]

[0152] [Fabrication of Cog V-Belt] (Example 1) Using the above-mentioned core wire and reinforcing fabric precursor, an uncrosslinked rubber sheet for the first rubber layer (R8, sheet thickness 9.6 mm), an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 2.4 mm), an uncrosslinked rubber sheet for the stretch rubber layer (R3, sheet thickness 1.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R15, sheet thickness 1.0 mm), a raw edge cogged V-belt of Example 1 was fabricated by the manufacturing method described as (Second Manufacturing Method) in the above-mentioned [Modes for Carrying Out the Invention]. Crosslinking was performed at 180°C and 0.9 MPa for 30 minutes to produce a crosslinked belt sleeve with a predetermined cog portion formed on the outer circumference. The obtained crosslinked belt sleeve was cut to a width of 50.8 mm with a cutter, and the sides were further cut into a V shape at a V angle of 28°. Then, the inner and outer circumferences were reversed to obtain a low-edge cogged V-belt (size: top width 50.8 mm, thickness 21.0 mm, belt length 2113 mm) with cogs formed on the inner circumference. In the obtained belt, the cog height (H １ ) is 12.6 mm, center valley thickness (H ２ ) is 5.4 mm (H １ +H２ The total thickness was 18.0 mm. Regarding the thickness of each layer, the compression rubber layer was 16.6 mm thick, the adhesive rubber layer was 2.8 mm thick, and the stretch rubber layer was 1.6 mm thick (total thickness 21.0 mm).

[0153] (Example 2) A raw edge cogged V-belt was manufactured in the same manner as in Example 1, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 8.4 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 3.6 mm.

[0154] (Example 3) A raw edge cogged V-belt was manufactured in the same manner as in Example 1, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 7.2 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 4.8 mm.

[0155] (Example 4) A raw edge cogged V-belt was manufactured in the same manner as in Example 1, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 4.8 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 7.2 mm.

[0156] (Example 5) A raw edge cogged V-belt was manufactured in the same manner as in Example 1, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 3.6 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 8.4 mm.

[0157] (Comparative Example 1) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the compressed rubber layer was formed using only one type of uncrosslinked rubber sheet (R3, sheet thickness 12.0 mm).

[0158] (Comparative Example 2) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the compressed rubber layer was formed using only one type of uncrosslinked rubber sheet (R8, sheet thickness 12.0 mm).

[0159] (Comparative Example 3) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the compressed rubber layer was formed from an uncrosslinked rubber sheet for the first rubber layer (R3, sheet thickness 7.2 mm) and a crosslinked rubber sheet for the second rubber layer (R8, sheet thickness 4.8 mm).

[0160] (Comparative Example 4) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the compressed rubber layer was formed from an uncrosslinked rubber sheet for the first rubber layer (R11, sheet thickness 7.2 mm) and an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 4.8 mm).

[0161] (Example 6) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6.

[0162] (Example 7) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R7.

[0163] (Example 8) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R9.

[0164] (Example 9) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R10.

[0165] (Example 10) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R1.

[0166] (Example 11) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R2.

[0167] (Example 12) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R4.

[0168] (Example 13) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R5.

[0169] (Example 14) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6 (sheet thickness 9.6 mm) and the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R1 (sheet thickness 2.4 mm).

[0170] (Example 15) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R10 (sheet thickness 3.6 mm) and the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R5 (sheet thickness 8.4 mm).

[0171] (Example 16) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R12.

[0172] (Example 17) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R13.

[0173] (Example 18) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R14.

[0174] (Example 19) A low-edge cogged V-belt was prepared in the same manner as in Example 3, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R1.

[0175] (Example 20) A low-edge cogged V-belt (size: top width 63.5 mm, thickness 30.0 mm, belt length 2168 mm) was obtained in the same manner as in Example 1, except that an uncrosslinked rubber sheet for the first rubber layer (R8, sheet thickness 10.2 mm), an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 6.8 mm), an uncrosslinked rubber sheet for the stretch rubber layer (R3, sheet thickness 2.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R15, sheet thickness 1.0 mm) were used. １ ) is 18.3 mm, center valley thickness (H ２ ) is 7.7 mm (H １ +H２ The total thickness was 26.0 mm. Regarding the thickness of each layer, the compression rubber layer was 24.6 mm thick, the adhesive rubber layer was 2.8 mm thick, and the stretch rubber layer was 2.6 mm thick (total thickness 30.0 mm).

[0176] (Example 21) A low-edge cogged V-belt (size: top width 76.2 mm, thickness 36.0 mm, belt length 2279 mm) was obtained in the same manner as in Example 1, except that an uncrosslinked rubber sheet for the first rubber layer (R8, sheet thickness 12.6 mm), an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 8.4 mm), an uncrosslinked rubber sheet for the stretch rubber layer (R3, sheet thickness 2.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R15, sheet thickness 1.0 mm) were used. １ ) is 23.0 mm, center valley thickness (H ２ ) is 9.3 mm (H １ +H ２ The total thickness was 32.3 mm. Regarding the thickness of each layer, the compression rubber layer was 30.6 mm thick, the adhesive rubber layer was 2.8 mm thick, and the stretch rubber layer was 2.6 mm thick (total thickness 36.0 mm).

[0177] (Example 22) A low-edge cogged V-belt (size: top width 44.5 mm, thickness 18.0 mm, belt length 2168 mm) was obtained in the same manner as in Example 1, except that an uncrosslinked rubber sheet for the first rubber layer (R8, sheet thickness 8.0 mm), an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 2.0 mm), an uncrosslinked rubber sheet for the stretch rubber layer (R3, sheet thickness 1.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R15, sheet thickness 1.0 mm) were used. １ ) is 11.0 mm, center valley thickness (H ２ ) is 4.0 mm (H １ +H ２ The total thickness was 15.0 mm. Regarding the thickness of each layer, the compression rubber layer was 13.6 mm thick, the adhesive rubber layer was 2.8 mm thick, and the stretch rubber layer was 1.6 mm thick (total thickness 18.0 mm).

[0178] (Example 23) A raw edge cogged V-belt was manufactured in the same manner as in Example 22, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 7.0 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 3.0 mm.

[0179] (Example 24) A raw edge cogged V-belt was manufactured in the same manner as in Example 22, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 6.0 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 4.0 mm.

[0180] (Example 25) A raw edge cogged V-belt was manufactured in the same manner as in Example 22, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 4.0 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 6.0 mm.

[0181] (Example 26) A raw edge cogged V-belt was manufactured in the same manner as in Example 22, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 3.0 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 7.0 mm.

[0182] (Comparative Example 5) A low-edge cogged V-belt was manufactured in the same manner as in Example 22, except that the compressed rubber layer was formed using only one type of uncrosslinked rubber sheet (R3, sheet thickness 10.0 mm).

[0183] (Comparative Example 6) A low-edge cogged V-belt was manufactured in the same manner as in Example 22, except that the compressed rubber layer was formed using only one type of uncrosslinked rubber sheet (R8, sheet thickness 10.0 mm).

[0184] (Comparative Example 7) A low-edge cogged V-belt was manufactured in the same manner as in Example 22, except that the compression rubber layers were formed from an uncrosslinked rubber sheet for the first rubber layer (R3, sheet thickness 6.0 mm) and an uncrosslinked rubber sheet for the second rubber layer (R8, sheet thickness 4.0 mm).

[0185] (Comparative Example 8) A low-edge cogged V-belt was manufactured in the same manner as in Example 22, except that the compressed rubber layer was formed from an uncrosslinked rubber sheet for the first rubber layer (R11, sheet thickness 6.0 mm) and an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 4.0 mm).

[0186] (Example 27) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6.

[0187] (Example 28) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R7.

[0188] (Example 29) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R9.

[0189] (Example 30) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R10.

[0190] (Example 31) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R1.

[0191] (Example 32) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R2.

[0192] (Example 33) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R4.

[0193] (Example 34) A low-edge cogged V-belt was prepared in the same manner as in Example 24, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R5.

[0194] (Example 35) A low-edge cogged V-belt was manufactured in the same manner as in Example 22, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6 (sheet thickness 8.0 mm) and the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R1 (sheet thickness 2.0 mm).

[0195] (Example 36) A low-edge cogged V-belt was manufactured in the same manner as in Example 22, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R10 (sheet thickness 3.0 mm) and the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R5 (sheet thickness 7.0 mm).

[0196] (Example 37) A low-edge cogged V-belt (size: top width 50.8 mm, thickness 26.0 mm, belt length 2118 mm) was obtained in the same manner as in Example 1, except that an uncrosslinked rubber sheet for the first rubber layer (R8, sheet thickness 12.0 mm), an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 3.0 mm), an uncrosslinked rubber sheet for the stretch rubber layer (R3, sheet thickness 2.6 mm), and an uncrosslinked rubber sheet for the adhesive rubber layer (R15, sheet thickness 1.0 mm) were used. １ ) is 13.5 mm, center valley thickness (H ２ ) is 8.5 mm (H １ +H ２ The total thickness was 22.0 mm. Regarding the thickness of each layer, the compression rubber layer was 20.6 mm, the adhesive rubber layer was 2.8 mm, and the stretch rubber layer was 2.6 mm (total thickness 26.0 mm).

[0197] (Example 38) A raw edge cogged V-belt was manufactured in the same manner as in Example 37, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 10.5 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 4.5 mm.

[0198] (Example 39) A raw edge cogged V-belt was manufactured in the same manner as in Example 37, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 9.0 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 6.0 mm.

[0199] (Example 40) A low-edge cogged V-belt was manufactured in the same manner as in Example 37, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 6.0 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 9.0 mm.

[0200] (Example 41) A raw edge cogged V-belt was manufactured in the same manner as in Example 37, except that the thickness of the uncrosslinked rubber sheet for the first rubber layer was 4.5 mm and the thickness of the uncrosslinked rubber sheet for the second rubber layer was 10.5 mm.

[0201] (Comparative Example 9) A low-edge cogged V-belt was manufactured in the same manner as in Example 37, except that the compressed rubber layer was formed using only one type of uncrosslinked rubber sheet (R3, sheet thickness 15.0 mm).

[0202] (Comparative Example 10) A low-edge cogged V-belt was manufactured in the same manner as in Example 37, except that the compressed rubber layer was formed using only one type of uncrosslinked rubber sheet (R8, sheet thickness 15.0 mm).

[0203] (Comparative Example 11) A low-edge cogged V-belt was manufactured in the same manner as in Example 37, except that the compression rubber layers were formed from an uncrosslinked rubber sheet for the first rubber layer (R3, sheet thickness 9.0 mm) and an uncrosslinked rubber sheet for the second rubber layer (R8, sheet thickness 6.0 mm).

[0204] (Comparative Example 12) A low-edge cogged V-belt was manufactured in the same manner as in Example 37, except that the compression rubber layers were formed from an uncrosslinked rubber sheet for the first rubber layer (R11, sheet thickness 9.0 mm) and an uncrosslinked rubber sheet for the second rubber layer (R3, sheet thickness 6.0 mm).

[0205] (Example 42) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6.

[0206] (Example 43) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R7.

[0207] (Example 44) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R9.

[0208] (Example 45) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R10.

[0209] (Example 46) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R1.

[0210] (Example 47) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R2.

[0211] (Example 48) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R4.

[0212] (Example 49) A low-edge cogged V-belt was prepared in the same manner as in Example 39, except that the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R5.

[0213] (Example 50) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R6 (sheet thickness 12.0 mm) and the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R1 (sheet thickness 3.0 mm).

[0214] (Example 51) A low-edge cogged V-belt was manufactured in the same manner as in Example 1, except that the rubber composition of the uncrosslinked rubber sheet for the first rubber layer was R10 (sheet thickness 4.5 mm) and the rubber composition of the uncrosslinked rubber sheet for the second rubber layer was R5 (sheet thickness 10.5 mm).

[0215] The evaluation results of the belts obtained in the examples and comparative examples are shown in Tables 4 to 20.

[0216]

[0217]

[0218]

[0219]

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227]

[0228]

[0229]

[0230]

[0231]

[0232]

[0233] <Verification Results in Tables 4 and 5> (Comparative Examples 1 and 2) Comparative Example 1 is an example of a belt in which the entire rubber layer forming the compression rubber layer is made only of R3 (crosslinked rubber) with a relatively high modulus of elasticity (3.2 MPa). Deformation resistance and abrasion resistance were good (rating a), but the cog valley crack resistance was unsatisfactory (rating d) due to the rigidity around the cog valleys, resulting in an overall unsatisfactory rating (rank D).

[0234] Comparative Example 2 is an example of a belt in which the entire rubber layer forming the compression rubber layer is made solely of R8 (crosslinked rubber) with a relatively low modulus of elasticity (2.2 MPa). While the resistance to cog valley cracking was good (rated a), the abrasion resistance was rated c and the deformation resistance was rated d (failed). Therefore, the overall rating was a failure (rank D).

[0235] (Examples 1-5) In contrast, the belts of the examples are examples in which the compression rubber layer is formed of two layers: a first rubber layer (relatively low modulus of elasticity) and a second rubber layer (relatively high modulus of elasticity). Examples 1-5 are examples in which the ratio of the first rubber layer to the second rubber layer is varied, and the ratio was indicated by the ratio of the area occupied by the first rubber layer to the total area of ​​the compression rubber layer (first rubber layer and second rubber layer) in a cross-sectional view in the thickness direction along the circumferential direction of the belt (area ratio of the first rubber layer).

[0236] In Examples 1 to 5, the area ratio of the first rubber layer was varied to 80% (Example 1), 70% (Example 2), 60% (Example 3), 40% (Example 4), and 30% (Example 5). As a result, it was observed that as the area ratio of the first rubber layer decreased, deformation resistance and abrasion resistance improved, while cog valley crack resistance tended to decrease. In particular, when the area ratio of the first rubber layer was 60% (Example 3), deformation resistance, abrasion resistance, and cog valley crack resistance all received an "a" rating (overall A rank), demonstrating excellent balance. Even with other area ratios of the first rubber layer, the overall rating was at an acceptable level (A to C rank), confirming the effectiveness of forming the compression rubber layer with two layers: a first rubber layer (relatively low modulus of elasticity) and a second rubber layer (relatively high modulus of elasticity).

[0237] (Comparative Example 3) On the other hand, Comparative Example 3 is formed with two layers of compression rubber, a first rubber layer and a second rubber layer, but with the opposite of Example 3, the magnitudes of the elastic moduli of the first and second rubber layers are reversed. That is, the first rubber layer is formed with a relatively high elastic modulus (3.2 MPa) and the second rubber layer is formed with a relatively low elastic modulus (2.2 MPa). As a result, the deformation resistance and abrasion resistance were good (rating a), but the cog valley crack resistance was unsatisfactory (rating d) because the area around the cog valley was rigid, and the overall rating was unsatisfactory (rank D).

[0238] (Comparative Example 4) In Comparative Example 4, the compression rubber layer is also formed of two layers, a first rubber layer and a second rubber layer. However, compared to Example 3, the first rubber layer is formed of a layer that does not contain short fibers (resulting in an even lower modulus of elasticity). The area around the cog valleys became more flexible, resulting in good resistance to cog valley cracking (rating a). However, it was too flexible, so deformation resistance could not be guaranteed (rating d), and abrasion resistance could not be guaranteed because it did not contain short fibers (rating d). Therefore, it was judged to be a failure (rank D) in the overall evaluation.

[0239] <Verification Results in Table 6> (Examples 6-9) In Examples 1-5, Example 3 (area ratio of the first rubber layer: 60%) had the best balance of lateral pressure resistance, abrasion resistance, and cog valley crack resistance. Examples 6-9 are examples of belts in which the elastic modulus (flexural modulus) of the first rubber layer was varied. The variation in elastic modulus was adjusted by varying the proportion of short fibers contained in the first rubber layer to 15 parts by mass (Example 6), 20 parts by mass (Example 7), 25 parts by mass (Example 3), 30 parts by mass (Example 8), and 35 parts by mass (Example 9). As a result of varying the flexural modulus of the first rubber layer to 1.9 MPa (Example 6), 2.0 MPa (Example 7), 2.2 MPa (Example 3), 2.5 MPa (Example 8), and 2.7 MPa (Example 9), it was observed that as the flexural modulus of the first rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance tended to decrease. In particular, when the flexural modulus of the first rubber layer was 2.2 to 2.5 MPa, the deformation resistance, abrasion resistance, and cog valley crack resistance all received an "a" rating (an overall "A" rank), indicating excellent balance. Even when the flexural modulus of the first rubber layer was at other levels, the overall rating was at an acceptable level (A to C rank). From these results, it can be said that the flexural modulus of the first rubber layer is preferably in the range of 1.5 to 3.0 MPa (particularly 2.0 to 2.5 MPa) in terms of flexural modulus (in the direction parallel to the short fibers). Furthermore, the proportion of short fibers contained in the first rubber layer is preferably in the range of 15 to 35 parts by mass (preferably 20 to 30 parts by mass, and even more preferably 25 to 30 parts by mass).

[0240] <Verification Results in Table 7> (Examples 10-13) Examples 10-13 are examples of belts in which the elastic modulus (flexural modulus) of the second rubber layer is varied, compared to the configuration of Example 3 (area ratio of the first rubber layer: 60%). The variation in elastic modulus was adjusted by varying the proportion of short fibers contained in the second rubber layer to 10 parts by mass (Example 10), 15 parts by mass (Example 11), 20 parts by mass (Example 3), 25 parts by mass (Example 12), and 30 parts by mass (Example 13). As a result of varying the flexural modulus of the second rubber layer to 2.9 MPa (Example 10), 3.0 MPa (Example 11), 3.2 MPa (Example 3), 3.3 MPa (Example 12), and 3.5 MPa (Example 13), it was observed that as the flexural modulus of the second rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance tended to decrease. In particular, when the flexural modulus of the second rubber layer was 3.2 to 3.3 MPa, the deformation resistance, abrasion resistance, and cog valley crack resistance all received an "a" rating (an overall "A" rank), indicating excellent balance. Even when the flexural modulus of the second rubber layer was at other levels, the overall rating was at an acceptable level (A to C rank). From these results, it can be said that the flexural modulus (in the direction parallel to the short fibers) of the second rubber layer is in a suitable range of 2.5 to 4.0 MPa (preferably 3.0 to 3.3 MPa, and more preferably 3.2 to 3.3 MPa). Furthermore, the proportion of short fibers contained in the first rubber layer is in a suitable range of 10 to 30 parts by mass (preferably 15 to 25 parts by mass, and more preferably 20 to 25 parts by mass).

[0241] <Verification Results in Table 8> (Examples 14 and 15) Examples 14 and 15 are examples in which the relationship (combination) between the area ratio of the first rubber layer, the elastic modulus of the first rubber layer (the proportion of short fibers contained in the first rubber layer), and the elastic modulus of the second rubber layer (the proportion of short fibers contained in the second rubber layer) was verified.

[0242] Example 14 is an example that combines conditions where the area ratio of the first rubber layer is large (80%), the flexural modulus of the first rubber layer is small [1.9 MPa (15 parts by mass of short fibers)], and the flexural modulus of the second rubber layer is small [2.9 MPa (10 parts by mass of short fibers)]. In this combination, the elastic modulus of the entire compression rubber layer is near the lower limit of the acceptable level. Even under these conditions, the resistance to cog valley cracking is good (rated a), and the abrasion resistance and deformation resistance are also rated c (acceptable), confirming that the overall rating is also at an acceptable level (rank C).

[0243] Conversely, Example 15 is an example that combines conditions where the area ratio of the first rubber layer is small (30%), the flexural modulus of the first rubber layer is large [2.7 MPa (35 parts by mass of short fibers)], and the flexural modulus of the second rubber layer is large [3.5 MPa (30 parts by mass of short fibers)]. In this combination, the elastic modulus of the entire compressed rubber layer is near the upper limit of the acceptable level. Even under these conditions, the abrasion resistance and deformation resistance are good (rated a), and the cog valley crack resistance is rated c (acceptable), confirming that the overall rating is also at an acceptable level (rank C).

[0244] <Verification Results in Table 9> (Examples 16-19) Compared to the belt of Example 3, in which the second rubber layer was formed with rubber composition R3 (flexural modulus of elasticity 3.2 MPa) containing 20 parts by mass of aramid short fibers and the first rubber layer was formed with rubber composition R8 (flexural modulus of elasticity 2.2 MPa) containing 25 parts by mass of nylon short fibers, in Example 16 the rubber composition forming the first rubber layer was changed to R12 (PET short fibers, flexural modulus of elasticity 2.0 MPa), and in Example 17 the rubber composition forming the first rubber layer was changed to R13 (cotton short fibers, flexural modulus of elasticity 2.1 MPa). In Example 18 the rubber composition forming the second rubber layer was changed to R14 (PBO short fibers, flexural modulus of elasticity 3.3 MPa). Furthermore, in Example 19 the first rubber layer was formed with rubber composition R1 (flexural modulus of elasticity 2.1 MPa), which has a lower aramid short fiber content than R3.

[0245] As a result, a comparison between Example 3 and Examples 16 and 17 indicates that the combination of aramid staple fibers and nylon staple fibers is superior. Furthermore, even when the staple fibers were changed in Examples 16 to 19, the overall evaluation remained at an acceptable level (A or B rank), suggesting that regardless of the type of staple fiber, it is sufficient as long as the flexural modulus of the first rubber layer is smaller than that of the second rubber layer.

[0246] <Verification Results in Table 10> (Examples 20 and 21) Examples 20 and 21 are examples of belts with a larger scale (increased overall belt thickness H) compared to the configuration of Example 3 (overall belt thickness H of 21.0 mm). In both Example 20, where the belt thickness H was increased to 30 mm, and Example 21, where the belt thickness H was increased to 36 mm, the deformation resistance, wear resistance, and cog valley crack resistance all received an A rating (overall A rank), indicating excellent balance.

[0247] <Verification Results in Tables 11-15> (Examples 22-26) The variation in the ratio of the first rubber layer to the second rubber layer, which was verified in Examples 1-5 where the total belt thickness H was 21.0 mm, was also verified for a belt with a total belt thickness H of 18.0 mm. In other words, the variation in the ratio of the area occupied by the first rubber layer to the total rubber layer (area ratio of the first rubber layer) in a cross-sectional view in the thickness direction along the circumferential direction of the belt was also verified for a belt with a total belt thickness H of 18.0 mm.

[0248] In Examples 22 to 26, the area ratio of the first rubber layer was varied to 80% (Example 22), 70% (Example 23), 60% (Example 24), 40% (Example 25), and 30% (Example 26). The results showed that as the area ratio of the first rubber layer decreased, deformation resistance and abrasion resistance improved, while cog valley crack resistance tended to decrease. In particular, when the area ratio of the first rubber layer was 60% (Example 24), deformation resistance, abrasion resistance, and cog valley crack resistance all received an "a" rating (overall A rank), demonstrating excellent balance. From the results of Examples 22 to 26, the overall rating remained at an acceptable level (A to C rank) across a wide range of different area ratios of the first rubber layer, confirming the effectiveness of forming the compression rubber layer with two layers: a first rubber layer (relatively low modulus of elasticity) and a second rubber layer (relatively high modulus of elasticity).

[0249] (Comparative Examples 5-8) The effect of forming the compressed rubber layer in a specific layer, as demonstrated in Comparative Examples 1-4 where the total belt thickness H was 21.0 mm, was also verified for a belt with a total belt thickness H of 18.0 mm.

[0250] Comparative Example 5 is an example of a belt in which the entire rubber layer forming the compression rubber layer is made solely of R3 (crosslinked rubber) with a relatively high modulus of elasticity (3.2 MPa). Although the deformation resistance and abrasion resistance were good (rating a), the resistance to cog valley cracking was unsatisfactory (rating d) due to the rigidity around the cog valleys, resulting in an overall failure (rank D).

[0251] Comparative Example 6 is an example of a belt in which the entire rubber layer forming the compression rubber layer is made solely of R8 (crosslinked rubber) with a relatively low modulus of elasticity (2.2 MPa). While the resistance to cog valley cracking was good (rated a), the abrasion resistance was rated c and the deformation resistance was rated d (failed). Therefore, the overall rating was a failure (rank D).

[0252] On the other hand, Comparative Example 7 is formed with a compression rubber layer consisting of two layers, a first rubber layer and a second rubber layer, but with the elastic moduli of the first and second rubber layers reversed compared to Example 24. That is, the first rubber layer was formed with a relatively high elastic modulus (3.2 MPa) and the second rubber layer with a relatively low elastic modulus (2.2 MPa). As a result, the deformation resistance and abrasion resistance were good (rating a), but the cog valley crack resistance was unsatisfactory (rating d) due to the rigidity around the cog valleys, resulting in an overall failure (rank D).

[0253] Comparative Example 8 also forms a compressed rubber layer with two layers, a first rubber layer and a second rubber layer. However, compared to Example 24, the first rubber layer is formed from a layer that does not contain short fibers (resulting in an even lower modulus of elasticity). The increased flexibility around the cog valleys resulted in good resistance to cog valley cracking (rating a), but it was too flexible, failing to guarantee deformation resistance (rating d), and the absence of short fibers also failed to guarantee abrasion resistance (rating d). Therefore, it was judged as unsuccessful overall (rank D).

[0254] (Examples 27-30) The variation in the elastic modulus (flexural modulus) of the first rubber layer, which was verified in Examples 6-9 where the overall belt thickness H was 21.0 mm, was also performed on a belt with an overall belt thickness H of 18.0 mm.

[0255] In Examples 22 to 26, Example 24 (with a first rubber layer area ratio of 60%) showed the best balance of lateral pressure resistance, abrasion resistance, and cog valley crack resistance. In contrast, Examples 27 to 30 are examples of belts in which the elastic modulus (flexural modulus) of the first rubber layer was varied. Similar to Examples 6 to 9, as the flexural modulus of the first rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance tended to decrease. In particular, when the flexural modulus of the first rubber layer was 2.2 to 2.5 MPa, the balance of deformation resistance, abrasion resistance, and cog valley crack resistance was excellent. Similar to Examples 6 to 9, the elastic modulus of the first rubber layer showed a tendency to be in a suitable range of 1.5 to 3.0 MPa (preferably 2.0 to 2.5 MPa, and even more preferably 2.2 to 2.5 MPa) in terms of flexural modulus (in the direction parallel to the short fibers).

[0256] (Examples 31-34) The variation in the elastic modulus (flexural modulus) of the second rubber layer, which was verified in Examples 10-13 where the total belt thickness H was 21.0 mm, was also performed on a belt with a total belt thickness H of 18.0 mm.

[0257] In contrast to Example 24 (where the area ratio of the first rubber layer was 60%), Examples 31 to 34 are examples of belts in which the elastic modulus (flexural modulus) of the second rubber layer was varied. Similar to Examples 10 to 13, as the flexural modulus of the second rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance tended to decrease. In particular, when the flexural modulus of the first rubber layer was 3.2 to 3.3 MPa, an excellent balance of deformation resistance, abrasion resistance, and cog valley crack resistance was observed, and the elastic modulus of the second rubber layer was found to be in a suitable range of 2.5 to 4.0 MPa (preferably 3.0 to 3.3 MPa, and even more preferably 3.2 to 3.3 MPa) in terms of flexural modulus (in the direction parallel to the short fibers), similar to Examples 10 to 13.

[0258] (Examples 35 and 36) The relationship (combination) between the area ratio of the first rubber layer, the elastic modulus of the first rubber layer (the proportion of short fibers contained in the first rubber layer), and the elastic modulus of the second rubber layer (the proportion of short fibers contained in the second rubber layer), which was verified in Examples 14 and 15 where the total belt thickness H was 21.0 mm, was also verified for a belt with a total belt thickness H of 18.0 mm.

[0259] Example 35 is an example that combines conditions where the area ratio of the first rubber layer is large (80%), the flexural modulus of the first rubber layer is small [1.9 MPa (15 parts by mass of short fibers)], and the flexural modulus of the second rubber layer is small [2.9 MPa (10 parts by mass of short fibers)]. In this combination, the elastic modulus of the entire compressed rubber layer is near the lower limit of the acceptable level. Even under these conditions, the resistance to cog valley cracking is good (rated a), and the abrasion resistance and deformation resistance are also rated c (acceptable), confirming that the overall rating is also at an acceptable level (rank C).

[0260] Conversely, Example 36 is an example that combines conditions where the area ratio of the first rubber layer is small (30%), the flexural modulus of the first rubber layer is large [2.7 MPa (35 parts by mass of short fibers)], and the flexural modulus of the second rubber layer is large [3.5 MPa (30 parts by mass of short fibers)]. In this combination, the elastic modulus of the entire compressed rubber layer is near the upper limit of the acceptable level. Even under these conditions, the abrasion resistance and deformation resistance are good (rated a), and the cog valley crack resistance is rated c (acceptable), confirming that the overall rating is also at an acceptable level (rank C).

[0261] <Verification results in Tables 16-20> (Examples 37-41) The variation in the ratio of the first rubber layer to the second rubber layer (area ratio of the first rubber layer), which was verified in Examples 1-5 with an overall belt thickness H of 21.0 mm and Examples 22-26 with an H of 18.0 mm, was also performed on a belt with an overall belt thickness H of 26.0 mm.

[0262] In Examples 37 to 41, when the area ratio of the first rubber layer was varied to 80% (Example 37), 70% (Example 38), 60% (Example 39), 40% (Example 40), and 30% (Example 41), a similar trend was observed as in the case of belts with an overall thickness H of 21.0 mm (Examples 1 to 5) and 18.0 mm (Examples 22 to 26). That is, as the area ratio of the first rubber layer decreased, deformation resistance and abrasion resistance improved, while cog valley crack resistance decreased. In particular, when the area ratio of the first rubber layer was 60% (Example 39), a tendency was observed to be excellent in the balance of deformation resistance, abrasion resistance, and cog valley crack resistance. From the results of Examples 37 to 41, it was confirmed that the effect of forming the compression rubber layer with two layers, a first rubber layer (relatively low modulus of elasticity) and a second rubber layer (relatively high modulus of elasticity), was observed over a wide range of different area ratios of the first rubber layer.

[0263] (Comparative Examples 9-12) The effect of forming the compressed rubber layer with two specific layers, as verified in Comparative Examples 1-4 (with an overall belt thickness H of 21.0 mm) and Comparative Examples 5-8 (with an H of 18.0 mm), was also verified for a belt with an overall belt thickness H of 26.0 mm.

[0264] Comparative Example 9 is an example of a belt in which the entire rubber layer forming the compression rubber layer is made only of R3 (crosslinked rubber) with a relatively high modulus of elasticity (3.2 MPa). Comparative Example 10 is an example of a belt in which the entire rubber layer forming the compression rubber layer is made only of R8 (crosslinked rubber) with a relatively low modulus of elasticity (2.2 MPa). On the other hand, Comparative Example 11 is an example in which the compression rubber layer is made of two layers, a first rubber layer and a second rubber layer, but the magnitudes of the moduli of the first and second rubber layers are reversed compared to Example 39. That is, the first rubber layer is made of a layer with a relatively high modulus of elasticity (3.2 MPa), and the second rubber layer is made of a layer with a relatively low modulus of elasticity (2.2 MPa). Comparative Example 12 is also an example in which the compression rubber layer is made of two layers, a first rubber layer and a second rubber layer, but compared to Example 39, the first rubber layer is made of a layer that does not contain short fibers (and has an even lower modulus of elasticity). Comparative Examples 9 to 12 all showed similar trends to the cases of belts with overall thickness H of 21.0 mm and 18.0 mm, and all of them failed the overall assessment (rank D).

[0265] (Examples 42-45) The variation in the elastic modulus (flexural modulus) of the first rubber layer, which was verified in Examples 6-9 with an overall belt thickness H of 21.0 mm and Examples 27-30 with an H of 18.0 mm, was also performed on a belt with an overall belt thickness H of 26.0 mm.

[0266] Examples 42 to 45 are belts based on the configuration of Example 39, which showed the best balance of lateral pressure resistance, abrasion resistance, and cog valley crack resistance among Examples 37 to 41, with variations in the elastic modulus (flexural modulus) of the first rubber layer. Similar trends were observed for belts with an overall thickness H of 21.0 mm (Examples 6 to 9) and 18.0 mm (Examples 27 to 30). Specifically, as the flexural modulus of the first rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance decreased. In particular, when the flexural modulus of the first rubber layer was 2.2 to 2.5 MPa, the balance of deformation resistance, abrasion resistance, and cog valley crack resistance was excellent. The elastic modulus of the first rubber layer was also similarly suited to a range of 1.5 to 3.0 MPa (preferably 2.0 to 2.5 MPa, and even more preferably 2.2 to 2.5 MPa) in terms of flexural modulus (in the direction parallel to the short fibers).

[0267] (Examples 46-49) The variation in the elastic modulus (flexural modulus) of the second rubber layer, which was verified in Examples 10-13 with an overall belt thickness H of 21.0 mm and Examples 31-34 with an H of 18.0 mm, was also performed on a belt with an overall belt thickness H of 26.0 mm.

[0268] Examples 46 to 49 are belts based on the configuration of Example 39, but with varying elastic modulus (flexural modulus) of the second rubber layer. Similar trends were observed as in the cases of belts with an overall thickness H of 21.0 mm (Examples 10 to 13) and 18.0 mm (Examples 31 to 34). Specifically, as the flexural modulus of the second rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance decreased. In particular, when the flexural modulus of the first rubber layer was 3.2 to 3.3 MPa, the balance of deformation resistance, abrasion resistance, and cog valley crack resistance was excellent. The elastic modulus of the second rubber layer was also similarly suited to a range of 2.5 to 4.0 MPa (preferably 3.0 to 3.3 MPa, and even more preferably 3.2 to 3.3 MPa) in terms of flexural modulus (in the direction parallel to the short fibers).

[0269] (Examples 50 and 51) The relationship (combination) between the area ratio of the first rubber layer, the elastic modulus of the first rubber layer (the proportion of short fibers contained in the first rubber layer), and the elastic modulus of the second rubber layer (the proportion of short fibers contained in the second rubber layer), which was verified in Examples 14 and 15 with an overall belt thickness H of 21.0 mm and Examples 35 and 36 with an overall belt thickness H of 18.0 mm, was also verified for a belt with an overall belt thickness H of 26.0 mm.

[0270] Similar trends were observed in the cases of belts with an overall thickness H of 21.0 mm (Examples 14 and 15) and 18.0 mm (Examples 35 and 36). Specifically, as the flexural modulus of the first rubber layer increased, deformation resistance and abrasion resistance improved, while cog valley crack resistance decreased. Considering the results of Example 39, it was found that the balance of deformation resistance, abrasion resistance, and cog valley crack resistance was particularly excellent when the flexural modulus of the first rubber layer was 2.2 to 2.5 MPa. The elastic modulus of the first rubber layer was found to be in a suitable range of 1.5 to 3.0 MPa (preferably 2.0 to 2.5 MPa, and even more preferably 2.2 to 2.5 MPa) in terms of flexural modulus (in the direction parallel to the short fibers). In other words, even in Example 50, a combination in which the overall elastic modulus of the compressed rubber layer was near the lower limit of the acceptable level, it was confirmed that the overall judgment was at an acceptable level (C rank). Conversely, in Example 51, a combination in which the elastic modulus of the entire compression rubber layer was near the upper limit of the acceptable level, it was confirmed that the overall evaluation was at an acceptable level (C rank).

[0271] From the above results, it was found that, across a wide range of thicknesses of cog-equipped V-belts, the configuration of the present invention can suppress crack formation in the cog valleys by easing the stress at the bottom of the cog valleys (including the deepest part of the cog valleys), where stress tends to concentrate due to bending deformation, while maintaining lateral pressure resistance (deformation resistance) and wear resistance.

[0272] The cog-equipped V-belt of the present invention can be used as a V-belt (gear belt or CVT belt) in a transmission (continuously variable transmission) in which the gear ratio changes steplessly during belt operation, for example, as a CVT belt used in continuously variable transmissions of motorcycles, ATVs (quad bikes), snowmobiles, agricultural machinery, etc. In particular, the cog-equipped V-belt of the present invention is suitable as a CVT belt for heavy-duty agricultural machinery used in Europe and the United States, such as tillers, binders, combines, vegetable harvesters, threshing machines, bean cutters, corn crushers, potato harvesters, and beet harvesters, because it can ensure resistance to cog valley cracks even when subjected to large lateral pressure from the pulley.

[0273] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2024-232880 filed on 27 December 2024 and Japanese Patent Application No. 2025-257633 filed on 16 December 2025, the contents of which are incorporated herein by reference.

[0274] 1... Raw edge cogged V-belt 1a... Cog peaks 1b... Cog valleys 2... Compression rubber layer 2a... First rubber layer 2b... Second rubber layer 3... Core layer (adhesive rubber layer) 4... Core wire 5... Stretch rubber layer

Claims

1. A cogged V-belt having a cog portion on at least the inner circumference side, wherein the cog portion comprises at least a compression rubber layer, the compression rubber layer includes a first rubber layer on the inner circumference side of the belt and a second rubber layer on the outer circumference side of the belt than the first rubber layer, the first rubber layer is formed of a first crosslinked rubber composition comprising a first rubber component and first short fibers, the second rubber layer is formed of a second crosslinked rubber composition comprising a second rubber component and second short fibers, the first rubber layer and the second rubber layer are exposed to form a friction transmission surface, and the modulus of elasticity of the first rubber layer is lower than the modulus of elasticity of the second rubber layer.

2. The cog-equipped V-belt according to claim 1, wherein, in a cross-sectional view along the thickness direction of the belt longitudinal direction, the area ratio of the first rubber layer is 30 to 80% of the total area of ​​the compression rubber layer.

3. The cog-type V-belt according to claim 1 or 2, wherein the modulus of elasticity of the second short fiber is higher than the modulus of elasticity of the first short fiber.

4. The cog-type V-belt according to any one of claims 1 to 3, wherein the flexural modulus of the first rubber layer is 1.5 to 3 MPa and the flexural modulus of the second rubber layer is 2.5 to 4 MPa.

5. The cog-type V-belt according to any one of claims 1 to 4, wherein the proportion of the first short fibers is 15 to 35 parts by mass per 100 parts by mass of the first rubber component, and the proportion of the second short fibers is 10 to 30 parts by mass per 100 parts by mass of the second rubber component.

6. A cog-type V-belt according to any one of claims 1 to 5, which is a low-edge cog-type V-belt.

7. A belt transmission mechanism comprising a cog-equipped V-belt according to any one of claims 1 to 6 and a pulley, and provided in a belt-type continuously variable transmission.

8. The belt transmission mechanism according to claim 7, provided in a belt-type continuously variable transmission for large agricultural machinery.

Images